This invention pertains to the art of pneumatic tires, and more specifically to tires of the type having a breaker assembly comprising layers of cord fabric positioned beneath the tread. The breaker assembly includes wear strips to reduce wear in the crown region of the tire.
Pneumatic tires which are used in aircraft landing applications tend to wear along the centerline faster than the shoulder regions. When the tire wears through the breaker assembly, it must be removed and replaced.
In the art, various breaker assembly constructions have been set forth for use in pneumatic tires in efforts to enhance certain features of the tire. For example, U.S. Pat. No. 3,717,191 to Harrington et al. discloses a strip of rubber compound interposed between adjacent layers of cord fabric in a breaker assembly in order to change the stiffness of the tread between the crown and shoulder regions.
The arrangement of the bias angle of cords within a breaker ply with respect to the bias angle of cords within an additional breaker ply, as disclosed in U.S. Pat. No. 3,131,744 to Boussu et al., seeks to improve the roadability and riding comfort of a pneumatic tire.
In U.S. Pat. No. 3,762,458 to Yoshida et al., a pneumatic tire having a breaker layer of rubber coated glass cords sandwiched between two layers of short cut fiber reinforced rubber is disclosed. The pneumatic tire purportedly has improved abrasion resistance, cornering power and plunger resistance.
The present invention is directed to a pneumatic tire having an improved breaker assembly in order to resist wear in the crown region of the tire. The tire is particularly useful in aircraft applications in order to increase the number of landings the tire can achieve before replacement is necessary.
Generally, the pneumatic tire 10 includes a pair of beads (not shown), a carcass 18 extending from one bead to the other through a crown region of the tire, a tread 14 covering the outer side of the carcass 18, and a breaker assembly 20, 20A, 20B disposed between the tread 14 and the carcass 18 in the crown region of the tire. The breaker assembly 20, 20A, 20B includes wear strips. The construction of the wear strips and placement in the breaker assembly are set forth in the following preferred embodiments.
In one embodiment, the breaker assembly 20 comprises a first circumferentially extending breaker layer 24 which includes a central portion 26 located between a pair of extensions 30. Preferably, the central portion 26 comprises rubber material and the extensions 30 comprise cord fabric. The central portion acts as a wear strip to improve performance of the tire in aircraft landing applications.
A second circumferentially extending breaker layer 34 is positioned radially inwardly of the first layer 24. In a preferred embodiment, the second layer 34 is formed of cord fabric.
A third circumferentially extending breaker layer 40, located radially inwardly of the second layer 34, also includes a central portion 44 between a pair of extensions 48. The construction of the third layer 40 is similar to that of the first layer 24 in that the central portion 44 comprises rubber while the extensions 48 comprise cord fabric.
A fourth circumferentially extending breaker layer 52 is located radially inwardly of the third layer 40. The construction of the fourth layer 52 is similar to that of the second layer 34 and comprises cord fabric.
Another embodiment of the present invention includes at least three, and preferably four, circumferentially extending breaker layers 56, 60, 64, 68 comprising cord fabric. Interposed between adjacent layers in the central region of the breaker assembly 20A are circumferentially extending strips of rubber compound having a transverse width substantially less than that of the adjacent breaker layers such as narrow, relatively thin strips 72 of rubber whose transverse widths are essentially equal.
In yet another embodiment, first, second, and third circumferentially extending breaker layers 80, 84, 88 comprise cord fabric. Interposed between adjacent layers in the central region of the breaker assembly 20B are narrow wear strips 92 of cord fabric.
Definitions
For ease of understanding this disclosure the following terms are disclosed:
xe2x80x9cAxialxe2x80x9d and xe2x80x9caxiallyxe2x80x9d means the lines or directions that are parallel to the axis of rotation of the tire.
xe2x80x9cCircumferentialxe2x80x9d means lines or directions extending along the perimeter of the surface of the annular tire parallel to the equatorial plane EP and perpendicular to the axial direction.
xe2x80x9cEquatorial Plane (EP)xe2x80x9d means the plane perpendicular to the tire""s axis of rotation and passing through the center of its tread.
xe2x80x9cInnerxe2x80x9d means toward the inside of the tire and xe2x80x9couterxe2x80x9d means toward its exterior.
xe2x80x9cRadialxe2x80x9d and xe2x80x9cradiallyxe2x80x9d mean directions radially toward or away from the axis of rotation of the tire.
xe2x80x9cRubberxe2x80x9d means both natural and synthetic rubber compounds or a combination thereof.